Lean-burning, large-bore two-stroke natural gas engines have long been essential elements of the North American natural gas pipeline system and will continue to play a crucial role in natural gas transportation for the foreseeable future. However, with increasing pressure to reduce emissions, improving the performance of this aging engine fleet has become more critical than ever. Pre-Combustion Chambers (PCCs) are frequently implemented on these engines to improve ignition stability, extend the lean limit of operation, and significantly reduce harmful emissions such as nitrogen oxides (NOx) and...
Lean-burning, large-bore two-stroke natural gas engines have long been essential elements of the North American natural gas pipeline system and will continue to play a crucial role in natural gas transportation for the foreseeable future. However, with increasing pressure to reduce emissions, improving the performance of this aging engine fleet has become more critical than ever. Pre-Combustion Chambers (PCCs) are frequently implemented on these engines to improve ignition stability, extend the lean limit of operation, and significantly reduce harmful emissions such as nitrogen oxides (NOx) and hydrocarbons (HC). While PCCs help reduce the carbon footprint of pipeline compressor stations, ongoing research into the pathway toward reduced emissions re-mains essential, as many avenues are still to be explored. This study aims to further research into novel subsonic converging and supersonic converging-diverging PCC nozzle designs that could potentially reduce methane emissions. A computational fluid dynamics (CFD) model of Texas A&M’s Cooper Ajax E-565 large-bore natural gas lean burn two-stroke was utilized in a prechambered configuration for the study. Several converging nozzles of decreasing size and converging-diverging nozzles of various throat diameter, area expansion ratio, and shape were explored to produce PCC jets of different shape, spread, and level of penetration into the main combustion chamber (MCC). The resultant jet effects were then heavily analyzed for impacts to general cycle performance, such as main chamber pressure, temperature, NOx emissions, and methane emissions.